Contributions to the Chemistry of Boron, 231 . Synthesis and Structures of Borylated Hydrazines

The diboration of the diazene PhN = NSiMe 3 ( 15 ) by diborane( 4 ) derivatives provides a new synthetic route to N,N' ‐diborylated hydrazines. The product formed depends on the type of the diborane( 4 ) compound. Thus, addition of dimesityldiboron dichloride to 15 in a 1:1 ratio afforded (mesCIB)PhN‐N(SiMe 3 )(BClmes) ( 16 ) while bis(dimethyl‐amino)diboron dichloride was found to react in a 1:2 ratio to give a triazadiborolidine derivative 17 . In addition, it was demonstrated that in the solid state Me 2 N–N(BPh 2 ) 2 ( 8 ) is a derivative of a three‐membered dihydroazadiboriridine C while its isomer, (Ph 2 B)MeN–NMe(BPh 2 ) ( 7 ), forms no BN coordinative bond. The new 3,6‐difluoro‐1,2,4,5‐tetraza‐3,6‐diborine 13 shows a twist conformation. The molecular structures of all these compounds were determined by X‐ray crystal structure analysis, and the influence of the B substituent on the conformation is discussed.